1. Field of the Invention
The invention relates to data processing, and more particularly to data serialization.
2. Description of the Related Art
A serializer converts parallel input data to serial output data. The serializer is therefore widely used in data processing. When the serializer is used in application with high speed data transmission, the circuit components of the serializer must be made of current mode logics (CML). A current mode logic, however, has greater power consumption than that of a standard cell and the serializer made of current mode logics therefore has high power consumption. In addition, the current mode logic occupies a larger chip area than a standard cell, and the manufacturing costs of the serializer made of current mode logics is therefore high. To lower manufacturing costs and to increase the data transmission speed, a conventional serializer comprises both current mode logics and standard cells.
The operation of a serializer must be triggered by a clock signal. Ordinarily, when a serializer comprises both current mode logics and standard cells, the standard cells with a low data transmission speed are triggered by a full swing clock, and the current mode logics with a high data transmission speed are triggered by a differential clock. Ordinarily, a differential clock is generated by a phase-locked-loop (PLL) voltage controlled oscillator (VCO), and a differential-to-single circuit then converts the differential clock to a full swing clock. When the differential-to-single circuit converts the differential clock to the full swing clock, noises and corner variation are induced to the full swing clock. When the current mode logics and standard cells of the serializer are operated according to the differential clock and the full swing clock, the current mode logics cannot synchronously operate with the standard cells due to the corner variation between the differential clock and the full swing clock. Data errors are therefore induced, and the output data of the serializer comprises jitter induced by the noise of the full swing clock. Thus, a serializer operating with a differential clock and a full swing clock is therefore required to prevent output data from errors.